FEDERAL INVESTIGATIONS OF MINE ACCIDENTS, STRUCTURAL MATERIALS, AND FUELS.[1] By HERBERT M. WILSON, M. Am. Soc. C. E. With Discussion by Messrs. KENNETH ALLEN, HENRY KREISINGER, WALTER O. SNELLING, A. BARTOCCINI, H. G. STOTT, B. W. DUNN, and HERBERT M. WILSON.